* frame.h (struct frame): New fields `can_have_scrollbars' and

* frame.h (struct frame): New fields `can_have_scrollbars' and
	`has_vertical_scrollbars'.
	(FRAME_CAN_HAVE_SCROLLBARS, FRAME_HAS_VERTICAL_SCROLLBARS): New
	accessors, for both the MULTI_FRAME and non-MULTI_FRAME.
	(VERTICAL_SCROLLBAR_WIDTH, WINDOW_VERTICAL_SCROLLBAR,
	WINDOW_VERTICAL_SCROLLBAR_COLUMN,
	WINDOW_VERTICAL_SCROLLBAR_HEIGHT): New macros.
	* window.h (struct window): New field `vertical_scrollbar'.
	* xterm.h (struct x_display): vertical_scrollbars,
	judge_timestamp, vertical_scrollbar_extra: New fields.
	(struct scrollbar): New struct.
	(VERTICAL_SCROLLBAR_PIXEL_WIDTH, VERTICAL_SCROLLBAR_PIXEL_HEIGHT,
	VERTICAL_SCROLLBAR_LEFT_BORDER, VERTICAL_SCROLLBAR_RIGHT_BORDER,
	VERTICAL_SCROLLBAR_TOP_BORDER, VERTICAL_SCROLLBAR_BOTTOM_BORDER,
	CHAR_TO_PIXEL_WIDTH, CHAR_TO_PIXEL_HEIGHT, PIXEL_TO_CHAR_WIDTH,
	PIXEL_TO_CHAR_HEIGHT): New accessors and macros.
	* frame.c (make_frame): Initialize the `can_have_scrollbars' and
	`has_vertical_scrollbars' fields of the frame.
	* term.c (term_init): Note that TERMCAP terminals don't support
	scrollbars.
	(mouse_position_hook): Document new args.
	(set_vertical_scrollbar_hook, condemn_scrollbars_hook,
	redeem_scrollbar_hook, judge_scrollbars_hook): New hooks.
	* termhooks.h: Declare and document them.
	(enum scrollbar_part): New type.
	(struct input_event): Describe the new form of the scrollbar_click
	event type.  Change `part' from a Lisp_Object to an enum
	scrollbar_part.  Add a new field `scrollbar'.
	* keyboard.c (kbd_buffer_get_event): Pass appropriate new
	parameters to *mouse_position_hook, and make_lispy_movement.
	* xfns.c (x_set_vertical_scrollbar): New function.
	(x_figure_window_size): Use new macros to calculate frame size.
	(Fx_create_frame): Note that X Windows frames do support scroll
	bars.  Default to "yes".
	* xterm.c: #include <X11/cursorfont.h> and "window.h".
	(x_vertical_scrollbar_cursor): New variable.
	(x_term_init): Initialize it.
	(last_mouse_bar, last_mouse_bar_frame, last_mouse_part,
	last_mouse_scroll_range_start, last_mouse_scroll_range_end): New
	variables.
	(XTmouse_position): Use them to return scrollbar movement events.
	Take new arguments, for that purpose.
	(x_window_to_scrollbar, x_scrollbar_create,
	x_scrollbar_set_handle, x_scrollbar_remove, x_scrollbar_move,
	XTset_scrollbar, XTcondemn_scrollbars, XTredeem_scrollbar,
	XTjudge_scrollbars, x_scrollbar_expose,
	x_scrollbar_background_expose, x_scrollbar_handle_click,
	x_scrollbar_handle_motion): New functions to implement scrollbars.
	(x_term_init): Set the termhooks.h hooks to point to them.
	(x_set_window_size): Use new macros to calculate frame size.  Set
	vertical_scrollbar_extra field.
	(x_make_frame_visible): Use the frame accessor
	FRAME_HAS_VERTICAL_SCROLLBARS to decide if we need to map the
	frame's subwindows as well.
	(XTread_socket): Use new size-calculation macros from xterm.h when
	processing ConfigureNotify events.
	(x_wm_set_size_hint): Use PIXEL_TO_CHAR_WIDTH and
	PIXEL_TO_CHAR_HEIGHT macros.
	* ymakefile (xdisp.o): This now depends on termhooks.h.
	(xterm.o): This now depends on window.h.